Method of operating a centrifugal separator



Nov. 7, 1939. w, E, SMITH 2.179.436

METHOD OF OPERATING A CENTRIFUGAL SEPARATOR Filed Dec. 8, 1936 lNVENTOR WALTER E. SMITH BY H|S ATTORNEYS Patented Nov. 7, 1939 i I i UNITED STATES PATENT OFFICE METHOD OF OPERATING A GENTBIFUGAL SEPARATOR Walter E. Smith, Honolulu, Territory of Hawaii Application December 8, 1936, Serial No. 114,815 3 Claims. (01. 127-56) This invention relates to centrifugal machines sugar, the speed of the separator is built up until for separating sugar from the mother liquor and it is operating at 25 to 30% above the previousit is an object of this invention to provide an imly normal speeds for commercial separators of proved method of operation for a machine of the the same size, that is, the speed of a separator,

5 class described which secures a more nearly com- 40 inches in diameter, is raised to 1700 to 1900 5 plete separation of the mother liquor from the revolutions per minute. The object of the insugar and it is also an object of this invention to crease in speed is partly to increase the separation provide a machine of the type described of imdue to the increase in centrifugal force, but prinproved construction which permits of the operacipally to improve separation by reducing the tion of the machine in a manner to secure the viscosity of the materials by reason of increase 10 desired separation of the mother liquor from the in temperature caused by the heat generated by sugar. the air friction of the basket rotating at this In the drawing, which shows a separator arhigher speed. This increase in temp e is ranged for carrying out this invention, Fig. 1 is sumcient to materially reduce the viscosity and a view, partly in elevation and partly in vertical prevent any increase in the viscosity of the mo- 15 section of a machine constructed in accordance lasses so that the molasses is readily separated with this invention; and r from the sugar and a much more nearly com- Fig. 2 is a plan view of one of the closures for plete separation of the molasses from the sugar the top of the curb shown detached therefrom. is secured. As the increase in the temperature of In the process of separating sugar from the the molasses occurs when the film of molasses on 20 mother liquor or molasses in a centrifugal septhe sugar crystals is very thin there is very little,

arator, the extent to which the separation may if any, dissolving of the sugar in the heated mobe accomplished is limited by the viscosity of lass Up n the l of the separator at h the molasses which causes it to adhere to the start of the operation the air in the separator sugar crystals as a thin film even under extreme becomes saturated with moisture from the vapor centrifugal force. One way in which the visrising from the mother liquor and as the temperacosity of the molasses has been reduced,to render tu e o t e -a in t separator rises during the possible the complete removal thereof, has been Operation its ability to absorb moisture increases by the application of water or other suitable and there would be some tendency f h air in liquid to dilute the molasses but in this method he separator to absorb moisture f m he mosome of the sugar is dissolved in the liquid aplosses on the sugar and render it more viscous plied. A further method of reducing the viscosity but t d y can be Overcome y admitting of the molasses has been to heat the sugar and n am u f moisture. s in t f f st a molasses mixture hotter than the most desirable during the ope t sllihcicnt to p the Incistemperature of 108 F. befoiplacing the mixture e in the air at the saturation point bu insuf- 35 in the centrifugal machine. This method, howflcient t ppr ciably afl'ect the temp tur in ever, may cause redissolving of some of the sugar, the separator to provide pl steam whic especially when much molasses is present, and at W condense and dissolve some of the sugarthe speeds heretofore used, the mixture cools In the drawing there is shOWn a r fu al 40 during centrifuging and the molasses is considsep a ranged for the ca ry Out f his 40 erably cooler and its viscosity higher at the end venti n. u h a separator mprises a curb of the centrifuging when it is desired to have the l in which 8 basket 2 is supported for on by molasses heated and its viscosity low. she-ft l driven y a motor 5 Which is pp ed In accordance with this invention the mother by suitable supporting means, not shown. The

liquor and sugar are at the usual temperature of motor 6 is of suita design and P w r to drive 45 about 108 F. when placed in the separator and the basket lat the desired increased speed. The the separator is arranged to be closed so as to basket 2 is shown arranged to discharge through prevent the passage of air currents through the the openings 8 controlled by valves I0 to a chute sugar mass and separator and the loss of heat l21eadingto the usual conveyor, not shown. The

resulting therefrom. At the beginning of the chute I2 is sealed into the bottom of the curb I 50 operation the greater portion of the molasses is so as to prevent leakage of air into the .curb. A thrown 011 readily and as the speed is built up valve or damper I4 is mounted in the chute to the film of molasses on the sugar crystals beprevent admission of'air through the spot whil comes thinner. In order to insure substantially the separator is in operation.

complete separation of the molasses from the" To close theopening in the top of the curb 55 through which the basket is filled and through which the shaft 4 extends, semi-circular doors [6 are hinged to the inner rim of the top of the curb. The doors l6 meet along a diameter and are cut away at the centers of their meeting edges, as at [6, to fit about the shaft 4. The usual discharge spout [8 for the mother liquor or molasses is extended so that its mouth is below the level of the molasses maintained in the trough 20. Steam to maintain the air in the separator at the saturation point may be supplied to the curb through a steam line 22 which merely discharges inside the curb since it is not desired to apply the steam to the sugar to secure a washing efiect.

Closing the various openings in the manner shown prevents the passage of air currents through the separator and the sugar mass therein and the loss of heat resulting therefrom and the increasing of the temperature within the separator without the addition of a washing liquid, but with the degree of saturation maintained, makes themolasses suiflciently fluid to secure maximum separation thereof from the sugar without loss through the dissolving of the sugar in either the molasses or a washing fluid.

What is claimed is:

1. A step in a method of separating sugar from the mother liquor consisting of centrifuging the mother liquor from the sugar in a sealed centrifugal separator to prevent flow of air currents therethrough at a speed of rotation necessary to cause a rise in the temperature of the sugar mass sufiicient to increase the fluidity of the molasses during said separation.

2. In a method of separating sugar from the mother liquor the step of centrifuging the mother liquor from the sugar is a separator sealed against the passage of air currents therethrough while raising the temperature of the sugar mass by the operation of the separator at a speed necessary to cause a rise in the temperature of the sugar mass sufiicient to increase the fluidity of the molasses during said separation and maintaining the air in the separator in a saturated condition by the addition of moisture.

3. In a method of separating sugar from the mother liquor the steps of centrifuging the mother liquor from the sugar in a sealed separator while raising the temperature within the separator by the operation thereof at a speed necessary to cause a rise in the temperature of the sugar mass sufiicient to increase the fluidity of the molasses during said separation and maintaining the relative humidity of the air in the separator substantially constant.

WALTER E. sm'rn.

- CERTIFICATE OF CORRECTION. Patent No. 2,179,156. v Nov m 7, 959- WALTER E. SMITH.

It is hereby certified that error appears in the printed specification of-the above numbered patent requiring correction as follow s: Page 2, sec- 0nd column, line 9, claim a, for is read in; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of. the case in the Patent Office. v

Signed and sealed this 19th day of December, A. D. 1959,

Henry Van Arsdale, (Seal) Acting Commissioner of Patents. 

